The Biostatistics Core is designed to serve as a centralized resource for biostatistical expertise to support AIDS research at UCLA. The aims of this Core are to enhance HIV/AIDS research and to establish and foster long-term collaborations between clinical, basic and behavioral researchers and biostatisticians at UCLA. This collaboration improves the biostatistical aspects of the AIDS research undertaken at UCLA and ensures that AIDS investigators have access to expert statistical consultation and support, and that the most appropriate and up-to-date methods are used. The kinds of support range from simple consultations to longterm collaborations and grant writing. The Core provides support to AIDS research in the following areas: statistical modeling and expertise to researchers in basic science departments, survey designs and analysis of observational data to social science departments, design of experiments and analysis for interventional studies including protocol implementation and randomization, and data modeling and analysis for clinical departments. Further the Core fosters the development of biostatistical methodology for immediate use by researchers in these groups. The Core supports AIDS projects in numerous departments of the Schools of Medicine, Dentistry, Public Health, Nursing and Policy: Medicine, Health Services, Pediatrics, Human Genetics, Digestive Diseases, Ophthalmology, Microbiology and Immunology, Nursing, OB Gynecology, Hematology and Oncology, Public Policy, Epidemiology, and Psychiatry. A consequence of the emphasis on long-term collaborative interactions is that this will lead to grant submissions and funding from other sources, thus allowing the Biostatistics Core to be available to focus on establishing new collaborations and supporting new research.